Medical procedures for treating a variety of neurological conditions, for example, Parkinson's disease, essential tremor and dystonia, require access to the brain, typically through a burr hole formed in the cranium, for the insertion of deep brain stimulating electrodes. Burr holes may also be formed for the insertion of a delivery catheter, for example, to provide drug therapy for similar conditions, or an extraction catheter, for example, a hydrocephalus shunt. Stereotactic apparatus and procedures, which are known to those skilled in the art, may be employed by surgeons to locate inserted electrodes and/or drug delivery ports in target regions of the brain.
FIG. 1A is a schematic showing an exemplary stereotactic guidance system 100 (e.g. Medtronic Nexdrive Micropositioning Drive attached to the Medtronic Nexframe®) mounted to a patient's cranium 13. FIG. 1A illustrates a ring 120 of guidance system 100, which extends around a perimeter of a body portal, or burr hole 11 formed in cranium 13, supporting a socket assembly 140 to which a micropositioning drive 160 is attached. An anchoring mechanism 112 (FIG. 1B; e.g. the Medtronic StimLoc®) may be mounted around burr hole 11 and fastened to cranium 13, for example, via bone screws received through holes 106 of a base ring of mechanism 112, prior to attaching ring 120 of guidance system 100. FIG. 1A further illustrates an elongate therapy delivery lead or catheter 15 of a medical device being held within drive 160 for advancement through burr hole 11 and into the cranial space for positioning on a target region of the brain.
FIG. 1B illustrates elongate therapy delivery lead or catheter 15 of the device extending through anchoring mechanism 112, after guidance system 100 has been removed. FIG. 1B further illustrates therapy delivery lead or catheter 15 extending through a slot of mechanism 112 to be anchored between mechanism 112 and a cap that snaps into place thereover (not shown; e.g., the Medtronic StimLoc® cap). Those skilled in the art appreciate that a proximal length of therapy delivery lead or catheter 15, outside the cranial space, may be routed, beneath the scalp and subcutaneously, to a therapy generator of the device, for example, a generator 28 that is shown, in the schematic of FIG. 1C, implanted subcutaneously in proximity to the patient's clavicle. With further reference to FIG. 1C, a distal length 154 of therapy delivery lead or catheter 15, which has been advanced through burr hole 11, is shown including therapy delivery ports, or electrodes 26A, 26B positioned at the target region.